Common Problems With Farm Ponds

Introduction   |   Fish Kills   |   Muddy Water   |    Leaking Ponds   |   Wildlife

Leaking Ponds

• Page 1 - Leaking Ponds
• Page 2 - Compaction
• Page 3 - Clay Blankets
• Page 4 - Bentonite
• Page 5 - Chemical Additives
• Page 6 - Waterproofed Linings

Click here for a printable version of this publication: Sealing Leaking Ponds

Bentonite

Adding bentonite is another method of reducing seepage in soils containing high percentage of coarse-grained particles and not enough clay. Bentonite is a fine-textured colloidal clay. When wet, it absorbs several times its own weight of water and, at complete saturation, swells to as much as 8 to 20 times its original volume. Mixed in the correct proportions with well-graded coarse-grained material, thoroughly compacted, and then saturated, the particles of bentonite swell until they fill the pores to the point the mixture is nearly impervious to water. Upon drying, however, bentonite shrinks to its original volume resulting in cracks; therefore, sealing with bentonite is usually not recommended for ponds in which the water level is expected to fluctuate widely. A laboratory analysis of soil particle size distribution is required to decide the rate of application.

Before selecting this method of sealing a pond, find the nearest source of bentonite and investigate freight rates. If the source is far from the pond site, the cost may prohibit the use of bentonite.

As with other methods, clear all vegetation from the area to be sealed. Fill all holes or crevices, and use suitable fill material to cover and compact areas of exposed gravel.

The soil moisture level in the area to be treated is important. Investigate it before applying bentonite. You need an optimum, medium to low, moisture level for good compaction. If the area is too wet, postpone sealing until moisture conditions are satisfactory. If it is too dry, add water by sprinkling.

Spread the bentonite carefully and uniformly over the area to be treated at the rate determined by the laboratory analysis. This rate is usually 1 to 3 pounds per square foot area. Thoroughly mix the bentonite with the surface soil to a depth of at least 6 inches. A rototiller is best for this operation but you can use a disk or similar piece of equipment; then compact the area with four to six passes of a sheepsfoot roller.

If considerable time elapses between applying the bentonite and filling the pond, protecting the treated area against drying and cracking may be necessary. A mulch of straw or hay pinned to the surface by the final passes of the sheepsfoot roller gives this protection. Use rock riprap or other suitable material to protect areas where water inflow into the treated area is concentrated.

  Previous Page - Clay Blankets

Next Page - Chemical Additives